Summit Entertainment has released a second domestic trailer for Moon director Duncan Jones‘ second film Source Code, which premieres at SXSW on March 11. Check out the new trailer after the break.

Source Code stars Jake Gyllenhall as a soldier who is part of an experimental program to ferret out the origin of a terrorist attack on a train. His psyche is projected into the body of a passenger on the train, and he relives the attack multiple times as he tries to trace it back to the point of origin. Michelle Monaghan, Vera Farmiga and Jeffrey Wright all factor in as well.

Of the three major trailers we’ve seen I like the UK one best — it has a good balance of plot, effects and WTF factor. This one starts by explaining the basic plot premise right off the bat, rather than dropping you into a the source code reality. There are some new effects shots here, though the basic trajectory of the trailer is the same as the previous ones.

Here is the official plot synopsis released at AFM:

Captain Colter Stevens (Jake Gyllenhaal) wakes with a jolt to find himself on a commuter train heading into Chicago. Although the other passengers all seem to know him, he has absolutely no idea where – or even who – he is. The last thing Colter remembers is flying a helicopter mission in Iraq, but here he is in someone else’s life going through someone else’s morning commute. Before he can do anything an express train zooms by on the opposite track and a bomb explodes, seemingly killing Colter and all the other passengers. Colter comes to in an isolation chamber, strapped to a seat, and wearing his military flight suit. He still has no idea what’s happening, except that he’s being spoken to by mission controller Carol Goodwin (Vera Farmiga), who calmly recites a series of memory questions to which Colter is shocked to realize he knows the answers.

He learns he’s part of an operation called “Beleaguered Castle,” but before he can progress any further, Goodwin starts up the machinery and suddenly Colter is back on the train, at exactly the same time he first appeared there, once again speeding through Chicago with the same group of commuters. Colter figures he’s in some kind of simulation exercise, with his task being to find the bomber on board the train before it goes off again. Living the explosion over and over, Colter must uncover the identity of the bomber, while also figuring out what the alternative universe of “Beleaguered Castle” is. Adding to the puzzle, Colter uses the second chance opportunities to make peace with his father, and to find romance with a fellow passenger on the train.